The invention relates to an agricultural vehicle which is automatically steered through a program including means to correct for deviations in agricultural operations such as seeding, plowing the the like. In particular, a three-axis gimbal system carrying a gyroscope and accelerometers provides an input to a program which calibrates and compensates for errors.
Inertia guidance systems are well-known in the art and find primary use in ocean vessels and airborne and space vehicles. For example, an inertia navigation system is disclosed in U.S. Pat. No. 3,509,765 of K. M. Stevenson, Jr., et al. which issued May 5, 1970. Such system is of a type which determines position, velocity and acceleration to provide information concerning navigation of the vehicle incorporated in the system. An autopilot system for a boat which includes control means for the boat's rudder is disclosed in the U.S. Pat. No. 3,140,436 of July 7, 1964 to W. Hatch. Systems have also been used for monitoring the route traveled by a vehicle, such a system being described in a U.S. Pat. No. 3,786,422 of Jan. 15, 1974 to S. Lubkin. Another patent to R. Lewis U.S. Pat. No. 4,032,758 of June 28, 1977 directed to a compensated vehicle heading system discloses sensors for sensing a vehicle's dynamic movement and indicates acceleratormeters mounted on the vehicle may be utilized as well as gyroscopic mechaisms. Problems with responding to gyroscopes and the like have been noted in the prior art. Thus a patent to R. Schaberg U.S. Pat. No. 3,440,889 of Apr. 29, 1969 discloses a potentiometer type pickup device for a gyroscope mounted in a guided missle or other maneuverable craft which is capable of indicating movement of the craft about an axis and through more than 180 degrees in either direction from a reference heading. Other U.S. patents which indicate the state-of-the-art are U.S. Pat. Nos. 865,278; 1,067,808; 1,137,258; 1,279,471; 1,496,087; 2,342,655; 2,953,858; 3,229,376; 3,669,657; 3,753,296, and 3,911,255. In addition, attention is invited to French Pat. Nos. 2,251,048 and 2,305,771 and to Netherlands application No. 76.13082. However, the application of a programmed steering to an agricultural vehicle poses severe problems of accuracy within tolerances measured in inches both in traversing straight lines and in turning which are not present in fluid borne vehicles and which involve considerably more than simply indicating location or adherence to a predetermined route of travel.